Low noise capacitors

ABSTRACT

Relatively low noise capacitors are provided for surface mounted applications. Electro-mechanical vibrations generate audible noise, which are otherwise relatively reduced through modifications to MLCC device structures, and/or their mounting interfaces on substrates such as printed circuit boards (PCBs). Different embodiments variously make use of flexible termination compliance so that surface mounting has reduced amplitude vibrations transmitted to the PCB. In other instances, side terminal and transposer embodiments effectively reduce the size of the mounting pads relative to the case of the capacitor, or a molded enclosure provides standoff, termination compliance and clamping of vibrations.

PRIORITY CLAIM

This application claims the benefit of previously filed U.S. ProvisionalPatent Application entitled “LOW NOISE CAPACITORS,” assigned U.S. Ser.No. 62/010,488, filed Jun. 11, 2014, and which is incorporated herein byreference for all purposes.

FIELD OF THE SUBJECT MATTER

The presently disclosed technology relates to low noise capacitors andcorresponding methodologies. More particularly, the presently disclosedtechnology relates to construction and surface mounting of capacitordevices on substrates such as printed circuit boards (PCB's) so as toprovide both mechanical and electrical connection with relatively lownoise characteristics (i.e., electro-mechanical noise reduction).

BACKGROUND OF THE SUBJECT MATTER

High density mounting of electronic components on printed circuit boardsand other substrates is common in the electronics industry. Miniatureceramic surface mount type capacitors having multiple layers have beenused for some time in electronic devices such as cellular telephones,network routers, computers, and the like. The manufacturing techniquesof such devices must be precise to provide for the greatly reduced sizeof these devices, while still affording desirable electrical operatingcharacteristics.

More recently it has become desirable to provide further types ofcomponents and various sub-circuits in on-board mountable form. SeveralUnited States Patents are directed to various aspects of electroniccomponent manufacture and mounting techniques. For example, commonlyowned U.S. Pat. No. 5,889,445 (Ritter et al., entitled “MultilayerCeramic RC Device”) discloses RC devices which include a plurality offirst and second ceramic layers interleaved to form a stack. The ceramiclayers each include a suitable electrode structure of opposite polarityforming the equivalent of multiple two-plate capacitors. Knownembodiments of multilayer ceramic capacitors (MLCC's) are also shown,for example, in FIGS. 2 and 3 of commonly owned U.S. Pat. No. 7,352,563(Pelcak et al., entitled “Capacitor assembly”).

The diversity of modern technical applications creates a need forefficient electronic components and integrated circuits for use therein.Capacitors are a fundamental component used for filtering, decoupling,bypassing and other aspects of such modern applications which mayinclude wireless communications, high-speed processing, networking,circuit switching and many other applications. Dramatic increases in thespeed and packing density of integrated circuits has resulted inadvancements in decoupling capacitor technology.

When high-capacitance decoupling capacitors are subjected to the highfrequencies of many present applications, performance characteristicsbecome increasingly more important. Since capacitors are fundamental tosuch a wide variety of applications, their precision and efficiency isimperative. Many specific aspects of capacitor design have thus been afocus for improving the performance characteristics of capacitors.

A wide variety of conventional capacitors are available on the markettoday, and each provides a unique combination of performancecharacteristics well-suited for particular applications. For example,multilayer ceramic capacitors (MLCCs) are typically quite effective forfrequency filtering applications. It is quite common that these andother particular capacitor types will be used in a single integratedcircuit environment. In such instances, the different capacitors may beconnected, for example, in parallel on a printed circuit board (PCB) asdiscrete components. Such approach may require a relatively large amountof circuit space and separate mounting pads for each capacitor.

For some time, the design of various electronic components has beendriven by a general industry trend toward miniaturization and ease ofincorporation of components into new or existing applications. In suchregard, a need exists for smaller electronic components havingexceptional operating characteristics. For example, some applicationsrequire the use of passive devices exhibiting various characteristicsincluding capacitive, inductive, and/or resistive characteristics orcombination assemblies thereof, but are severely limited in the amountof space (known as “real estate”) such devices may occupy on a circuitboard. It is important that such devices or combinations be configuredfor maximum ease of physical and electrical attachment to such circuitboards while occupying the least amount of “real estate” possible. As aresult, efforts continue to strive for component miniaturization,orientation efficiency and other ways to save space and maximize boardreal estate in a PCB environment.

It may also be desirable to improve other capacitor performancecharacteristics, such as ESR (Equivalent Series Resistance), which isthe inherent resistance value of a capacitor.

Another capacitor characteristic that may affect circuit applications ispiezoelectric noise or electro-mechanical or acoustic noise, which isprevalent in many mounted MLCC applications. Low level piezoelectricnoise may be generated, for example, when the capacitor ceramics aresubjected to alternate voltages, which can cause mechanical vibrationsin the capacitor. The inherent nature of the ceramic material convertsthe mechanical vibrations to generally low-level electrical noise.Significant amounts of piezoelectric noise can have an effect on signalquality, especially in high frequency applications. As such, it is oftendesirable to reduce piezoelectric noise levels in circuit applications.

Capacitors deform in response to applied voltage (electric field) due toelectrostrictive behavior inherent in all dielectric materials, asexpressed by the following known equation:Strain=M _(ij)*Electric Field²

In general, high dielectric constant materials have highelectrostrictive coefficients. A CV (capacitance times voltage) ratingis related in part to the volumetric efficiency of a capacitor. Ingeneral, the higher the capacitance, the larger the volume of thecapacitor. Given some capacitance value, the higher the voltage rating,the larger the volume of the capacitor. Thus, when a capacitor has a“high CV rating”, that means that it is volumetrically efficient, andoffers a small physical size compared to other capacitor types. High CVcapacitors have evolved to have very thin internal layers, giving veryhigh electric field strength even at modest operating voltage.

Mechanical strain (vibrations) may be transferred from the capacitorthrough the solder terminals to PCB substrates. The capacitor acts as adriver, in essence, a drum stick, while the PCB behaves as a soundinginstrument, such as a drum head. Therefore, the predominant audiblenoise is generated by vibrations from the PCB, not the capacitor itself.

A converse effect, that is, vibrations on PCB coupled through terminalsto the capacitor, can also cause an AC-ripple voltage on the capacitor.Such an effect is called “microphonics” and can be a problem in specialcases.

Various approaches have been previously provided in attempts to reduceelectro-mechanical noise associated with mounted MLCC devices, andinclude such as minimizing solder amount (for mounting of device onto aPCB), turning the orientation of MLCC internal layers parallel to PCB,using lower K dielectric materials, increasing stand-off (leads),pre-mounting capacitors on substrate, increasing clamping force (forproviding larger inactive margins), and simply replacing the MLCCdevices with a different type of device such as a tantalum capacitor.Such approaches inherently involve various tradeoffs, for example, insome instances, increased costs or increased complexity of MLCC devicedesigns or mounting techniques.

Additional patent citations include U.S. Pat. No. 5,629,578 (Winzer etal., entitled “Integrated composite acoustic transducer array”), relatedto a multilayer structure which has associated noise cancellationfeatures, and U.S. Pat. No. 8,665,059 (Korony et al., entitled “HighFrequency Resistor”), related to a resistor having flexible terminationmaterial. See, also, Korony U.S. Application Publication No.2011/0090665 entitled “Thin Film Surface Mount Components” and HattoriU.S. Application Publication Nos. 2014/0016242 entitled “ElectronicComponent”, 2013/0299224 entitled “Ceramic Electronic Component andElectronic Device”, and 2013/0284507 entitled “Electronic Component.”

The presently disclosed subject matter relates generally to smallelectronic components adapted to be surface mounted on a larger circuitboard. More particularly, the subject matter may relate to a surfacemount capacitor device for use in a variety of applications. Accordingto industry practice, the size of a surface mount component is generallyexpressed as a number “XXYY,” with XX and YY being the length and width,respectively, in hundredths of an inch.

While various implementations of capacitor devices and associatedassemblies and mounting methodologies therefor have been developed, nodesign has emerged that generally encompasses all of the desiredcharacteristics as hereafter presented in accordance with the subjecttechnology.

SUMMARY OF THE SUBJECT MATTER

The presently disclosed subject matter recognizes and addresses severalof the foregoing issues, and others concerning certain aspects ofcapacitor devices. Thus, broadly speaking, an object of certainembodiments of the presently disclosed technology is to provide improveddesigns for certain capacitor components and component assembliesassociated with the implementation of surface mountable devices. Otherobjects, broadly speaking relate to providing low noise capacitors andrelated methodologies.

Other present objects relate to construction and surface mounting ofcapacitor devices on substrates such as printed circuit boards (PCB's)so as to provide both mechanical and electrical connection withimproved, relatively low noise characteristics (i.e., electro-mechanicalnoise reduction).

Aspects of other exemplary embodiments of the presently disclosedsubject matter provide improved electrical and mechanical coupling ofcertain surface mount devices to circuits or traces on a printed circuitboard on which the device may be mounted, for improved noise performancecharacteristics.

Still further aspects of yet still other embodiments of the presentlydisclosed subject matter provide enhancements to manufacturing and/ormounting methodologies associated with the use of surface mount typedevices.

Still further, it is to be understood that the presently disclosedtechnology equally applies to the resulting devices and structuresdisclosed and/or discussed herewith, as well as the correspondinginvolved methodologies.

Yet further aspects of still other embodiments of the presentlydisclosed subject matter provide compliant termination features fornoise reduction aspects. Other presently disclosed embodiments relate toadvantageous relocation of terminals of a surface mount capacitor. Stilladditional presently disclosed embodiments relate to enclosure of acapacitor, such as in an epoxy case. Yet other presently disclosedembodiments may relate to pre-mounting of capacitors on a so-calledtransposer component or element.

It is a further general object to provide relatively low manufacturingcosts combined with relatively improved noise reduction in surfacemounted capacitor devices.

Yet further still it should be appreciated that certain aspects of thepresently disclosed subject matter may be applied to individual activecomponents or combinations thereof with passive components. For example,active combinations including, but not limited to, amplifiers,oscillators, and other functional block assemblies may benefit from thepresently disclosed technology.

It is also an object to provide improved devices and/or associatedmethodologies resulting in low noise, surface mounted capacitor devicesuseful, for example, in audio circuits in hand-held electronics, inautomotive electronics, in computer disk drives, and useful in specialtyindustrial, aerospace, and medical applications.

One presently disclosed exemplary embodiment relates to a surfacemountable relatively low noise multilayer ceramic capacitor (MLCC)capacitor assembly. Such a capacitor assembly preferably comprises amain body having a plurality of conductive layers of respective firstand second polarities interleaved with a plurality of ceramic layers toform respective pairs of opposing capacitor plates in a stackedarrangement; and respective first and second polarity terminations onopposite ends of such main body and electrically connected,respectively, to such first and second polarity conductive layers.Further, such terminations include a compliant layer for relativelydampening vibrations between such capacitor assembly and a surface onwhich it is mounted for relatively reducing electro-mechanical noise.

In some such embodiments, such compliant layer may comprise a layer ofcompliant polymer. In various such embodiments, such compliant polymermay comprise a generally conductive polymer, or a conductive polymerwhich is a silver-polymer layer, or one which is one of silver, copperor nickel filled polymers.

In other alternatives of such embodiment, such surface may comprise asupporting substrate. In various such embodiments, such supportingsubstrate may comprise a printed circuit board, and such compliantpolymer layer may have a Modulus of Elasticity of generally less than 5GPa, so that surface mounting of such capacitor assembly has reducedamplitude vibrations transmitted to the printed circuit board, so as toprovide both mechanical and electrical connection with relatively lownoise characteristics.

In various alternatives of such embodiments, such terminations maycomprise a silver polymer over a relatively thinner flashing layer,and/or such flashing layer may comprise a copper layer, or furtheralternatively, such terminations may comprise a silver polymer over arelatively thinner copper flashing layer, and with a layer of platingover such silver polymer layer. In some such alternatives, such layer ofplating may comprise nickel-tin plating.

The presently disclosed subject matter is intended to equally relate tocorresponding and/or related methods. One such presently disclosedexemplary embodiment relates to methodology for relatively reducingelectro-mechanical noise associated with a surface mountable multilayerceramic capacitor (MLCC) capacitor assembly. Such exemplary methodologypreferably includes providing a main body having a plurality ofconductive layers of respective first and second polarities interleavedwith a plurality of ceramic layers to form respective pairs of opposingcapacitor plates in a stacked arrangement; and forming respective firstand second polarity terminations on opposite ends of such main body andelectrically connected, respectively, to such first and second polarityconductive layers. Further, preferably such terminations include acompliant layer for relatively dampening vibrations between suchcapacitor assembly and a surface on which it is mounted for relativelyreducing electro-mechanical noise.

In some alternatives of such exemplary methodology, such compliant layermay comprise a layer of compliant polymer. Per other alternatives, suchcompliant polymer may comprise generally conductive polymer comprisingone of silver, copper or nickel filled polymers.

Variations of such exemplary methodology may further include surfacemounting such capacitor assembly on a supporting substrate comprising aprinted circuit board, so that surface mounting of such capacitorassembly has reduced amplitude vibrations transmitted to the printedcircuit board, so as to provide both mechanical and electricalconnection with relatively low noise characteristics.

In other presently disclosed variations, such terminations may comprisea silver polymer over a relatively thinner copper flashing layer, or maycomprise a silver conductive polymer over a relatively thinner copperflashing layer, and with a layer of plating over such silver conductivepolymer layer.

Per yet another presently disclosed exemplary embodiment, a surfacemountable relatively low noise multilayer ceramic capacitor (MLCC)capacitor assembly preferably comprises a main body having a pluralityof conductive layers of respective first and second polaritiesinterleaved with a plurality of ceramic layers to form respective pairsof opposing capacitor plates in a stacked arrangement; respective firstand second polarity terminations on opposite ends of such main body andelectrically connected, respectively, to such first and second polarityconductive layers; and a molded case in which such main body is receivedwith such terminations supported on a surface, for relatively dampeningvibrations between such capacitor assembly and a surface on which it ismounted for relatively reducing electro-mechanical noise.

In some variations of such exemplary embodiment, such molded case maycomprise an epoxy case completely encapsulating such main body. In someinstances, such conductive layers may be arranged vertically relative toa surface on which such terminations are supported, though in otherinstances the arrangement may be other than vertical. In further suchvariations, such molded case may comprise an A-case package mounted as aland grid array style package on solder pads of a predetermined sizecase. In other alternatives, such predetermined size case may comprisedimensions of a 1206 A-case package, where such dimensions comprise thelength and width, respectively, of such case expressed in hundredths ofan inch. As understood by those of ordinary skill in the art, A-case isindustry terminology for a 1206-sized equivalent device. It should beappreciated that the presently disclosed subject matter is equallyapplicable to other sizes and arrangements. For example, it may also bepracticed with B-case (1210 equivalent size) and R- and N-case (0805equivalent size). Also, the presently disclosed subject matter may bepracticed to mount A-, B-, R- and N-case parts on industry standardmounting pads (1206, 1210, 0805 and 0805, respectively) and also tomount same A-, B-, R- and N-case on one size smaller mounting pads(1206, 0805, 0603 and 0603, respectively). This later method places thesolder pads under the part (aka, Land Grid Array style) and effectivelyeliminates the large solder fillet from the end of the molded capacitor,which in turn reduces clamping stress and vibrations coupled fromcapacitor to mounting substrate.

Per other alternatives, such surface may comprise a supportingsubstrate. In some instances, such supporting substrate may comprise aprinted circuit board, and such molded case may comprise a moldedpackage having a polymer coating and a lead frame. In some suchinstances, such main body may be received with such conductive layersarranged vertically relative to a surface on which such terminations aresupported, though in other arrangements they may be arranged other thanvertically, to decouple capacitor distortion from the printed circuitboard to dampen device noise by reducing the amplitude of vibrationstransmitted to the printed circuit board, so as to provide bothmechanical and electrical connection thereto with relatively low noisecharacteristics.

In other variations, such terminations may comprise nickel-tin platingover a copper film.

Another presently disclosed exemplary embodiments may relate tocorresponding methodology for relatively reducing electro-mechanicalnoise associated with a surface mountable multilayer ceramic capacitor(MLCC) capacitor assembly. An exemplary such methodology may compriseproviding a main body having a plurality of conductive layers ofrespective first and second polarities interleaved with a plurality ofceramic layers to form respective pairs of opposing capacitor plates ina stacked arrangement; forming respective first and second polarityterminations on opposite ends of such main body and electricallyconnected, respectively, to such first and second polarity conductivelayers; and placing such main body in a molded case with suchterminations supported on a surface, for relatively dampening vibrationsbetween such capacitor assembly and a surface on which it is mounted forrelatively reducing electro-mechanical noise.

In variations of the foregoing, such molded case may comprise an epoxycase completely encapsulating such main body. In some instances, suchconductive layers may be arranged vertically relative to a surface onwhich terminations are supported, though in other arrangements otherthan vertical may be practiced. In some other variations, such moldedcase may comprise an A-case package mounted as a land grid array stylepackage on solder pads of a predetermined size case.

Per other variations, such surface may comprise a supporting substrate,and/or such supporting substrate may comprise a printed circuit board,and such molded case may comprise a molded package having a polymercoating and a lead frame. In some instances such main body may bereceived with such conductive layers arranged vertically relative to asurface on which such terminations are supported, though in otherarrangements other than vertically may be practiced, to decouplecapacitor distortion from the printed circuit board to dampen devicenoise by reducing the amplitude of vibrations transmitted to the printedcircuit board, so as to provide both mechanical and electricalconnection thereto with relatively low noise characteristics.

In yet other variations, such terminations may comprise nickel-tinplating over a copper film, and/or the length of such terminations andthe location of attachments points thereof may be predetermined forfurther decoupling vibrations transmitted to the printed circuit boardfrom such capacitor assembly.

Another presently disclosed exemplary embodiment relates to a surfacemountable relatively low noise multilayer ceramic capacitor (MLCC)capacitor assembly, preferably comprising a main body having a pluralityof conductive layers of respective first and second polaritiesinterleaved with a plurality of ceramic layers to form respective pairsof opposing capacitor plates in a stacked arrangement; and respectivefirst and second polarity terminations on opposite sides of such mainbody and electrically connected, respectively, to such first and secondpolarity conductive layers with such terminations supported on asurface, for relatively reducing supportive and connective footprintbetween such capacitor assembly and a surface on which it is mounted forrelatively reducing vibration force transmission therebetween forreducing electro-mechanical noise.

In some variations of the foregoing, such surface may comprise asupporting substrate, and/or such supporting substrate may comprise aprinted circuit board, so that surface mounting of such capacitorassembly has reduced amplitude vibrations transmitted to the printedcircuit board, so as to provide both mechanical and electricalconnection with relatively low noise characteristics.

In other present alternatives, such terminations may comprise a layer ofnickel-tin plating, or may comprise nickel-tin plating over a copperfilm, and/or such copper film may comprise a relatively thick film ofcopper.

One presently disclosed exemplary corresponding method may relate tomethodology for relatively reducing electro-mechanical noise associatedwith a surface mountable multilayer ceramic capacitor (MLCC) capacitorassembly, preferably comprising providing a main body having a pluralityof conductive layers of respective first and second polaritiesinterleaved with a plurality of ceramic layers to form respective pairsof opposing capacitor plates in a stacked arrangement; formingrespective first and second polarity terminations on opposite sides ofsuch main body and electrically connected, respectively, to such firstand second polarity conductive layers; and supporting such terminationson a surface, wherein a relatively reduced supportive and connectivefootprint is formed between such capacitor assembly and such surface onwhich it is supported for relatively reducing vibration forcetransmission therebetween for reducing electro-mechanical noise.

In alternatives thereof, such surface may comprise a supportingsubstrate, and/or such supporting substrate may comprise a printedcircuit board, so that surface mounting of such capacitor assembly hasreduced amplitude vibrations transmitted to the printed circuit board,so as to provide both mechanical and electrical connection withrelatively low noise characteristics.

In other variations, such terminations may comprise a layer ofnickel-tin plating, and/or may comprise nickel-tin plating over a copperfilm. In some instances, such copper film may comprise a relativelythick film of copper.

Yet another presently disclosed exemplary embodiment may relate to asurface mountable relatively low noise multilayer ceramic capacitor(MLCC) capacitor assembly, preferably comprising a main body having aplurality of conductive layers of respective first and second polaritiesinterleaved with a plurality of ceramic layers to form respective pairsof opposing capacitor plates in a stacked arrangement; respective firstand second polarity terminations on such main body and electricallyconnected, respectively, to such first and second polarity conductivelayers; and a transposer mounting pad attached to such capacitorassembly with such transposer mounting pad supported on a surface, forrelatively reducing a supportive and connective footprint between suchcapacitor assembly and a surface by which it is supported for relativelyreducing vibration force transmission therebetween for reducingelectro-mechanical noise.

Per some alternatives of the foregoing, a side of such main body facingsuch surface may form a capacitor mounting pad; and such capacitorassembly may further include a solder mask between such capacitormounting pad and such transposer mounting pad.

Per other alternatives, such respective first and second polarityterminations may be formed on opposite ends of such main body.

In yet other variations, such surface may comprise a supportingsubstrate, and/or such supporting substrate may comprise a printedcircuit board, so that surface mounting of such capacitor assembly hasreduced amplitude vibrations transmitted to the printed circuit board,so as to provide both mechanical and electrical connection withrelatively low noise characteristics.

Per still other alternatives, such terminations may comprise a layer ofnickel-tin plating and/or may comprise nickel-tin plating over a copperfilm.

In other variations, the area of such transposer mounting pad may beapproximately one-half or less of the area of such capacitor mountingpad, to effectively reduce the size of the mounting pads relative to thecapacitor assembly.

Exemplary corresponding and/or related method may relate to methodologyfor relatively reducing electro-mechanical noise associated with asurface mountable multilayer ceramic capacitor (MLCC) capacitorassembly, preferably comprising providing a main body having a pluralityof conductive layers of respective first and second polaritiesinterleaved with a plurality of ceramic layers to form respective pairsof opposing capacitor plates in a stacked arrangement; formingrespective first and second polarity terminations on such main body andelectrically connected, respectively, to such first and second polarityconductive layers; and attaching a transposer mounting pad to suchcapacitor assembly and supporting such transposer mounting pad on asurface, for relatively reducing a supportive and connective footprintbetween such capacitor assembly and a surface by which it is supportedfor relatively reducing vibration force transmission therebetween forreducing electro-mechanical noise.

In variations of the foregoing, such attaching and supporting mayinclude pre-mounting such transposer mounting pad to such capacitorassembly before supporting such transposer mounting pad on a surface.

Per other alternatives, a side of such main body facing such surface mayform a capacitor mounting pad; and such methodology may further includeproviding a solder mask between such capacitor mounting pad and suchtransposer mounting pad.

Further alternatively, such respective first and second polarityterminations may be formed on opposite ends of such main body.

For other alternatives, such surface may comprise a supportingsubstrate, and/or such supporting substrate may comprise a printedcircuit board, so that surface mounting of such capacitor assembly hasreduced amplitude vibrations transmitted to the printed circuit board,so as to provide both mechanical and electrical connection withrelatively low noise characteristics.

In other variations, such terminations may comprise a layer ofnickel-tin plating and/or may comprise nickel-tin plating over a copperfilm. Per other alternatives of the foregoing, the area of suchtransposer mounting pad may be approximately one-half or less of thearea of such capacitor mounting pad, to effectively reduce the size ofthe mounting pads relative to the capacitor assembly.

Additional objects and advantages of the presently disclosed subjectmatter are set forth in, or will be apparent to those of ordinary skillin the art from, the detailed description herein. Also, it should befurther appreciated by those of ordinary skill in the art thatmodifications and variations to the specifically illustrated,referenced, and discussed features and/or steps hereof may be practicedin various embodiments and uses of the disclosed technology withoutdeparting from the spirit and scope thereof, by virtue of presentreference thereto. Such variations may include, but are not limited to,substitution of equivalent means, steps, features, or materials forthose shown, referenced, or discussed, and the functional, operational,or positional reversal of various parts, features, steps, or the like.

Still further, it is to be understood that different embodiments, aswell as different presently preferred embodiments, of this technologymay include various combinations or configurations of presentlydisclosed steps, features or elements, or their equivalents (includingcombinations of features, configurations, or steps thereof not expresslyshown in the figures or stated in the detailed description).

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling description of the presently disclosed subjectmatter, including the best mode thereof, directed to one of ordinaryskill in the art, is set forth in the specification, which makesreference to the appended figures, in which:

FIG. 1 illustrates a schematic view of an exemplary presently-devisedtest arrangement, for testing of either prior art devices or devicesconstructed and/or mounted in accordance with the presently disclosedtechnology;

FIGS. 2A, 2B, 2C, and 2D are various perspective and cross-sectionalviews of prior art multi-layer ceramic capacitor (MLCC) devices;

FIG. 3 is a graph of comparative sound pressure testing resulting fromuse of a testing arrangement as represented by present FIG. 1, performedon existing MLCC devices such as represented by present FIGS. 2A through2D;

FIGS. 4A and 4B are schematic representations of aspects of mountingMLCC devices on printed circuit boards (PCBs);

FIG. 5A is a cross-sectional view of exemplary first embodiment of thepresently disclosed subject matter, involving compliant terminationtechnology, for relatively reducing electro-mechanical noise, and FIG.5B is a graph of testing resulting from use of a testing arrangement asrepresented by present FIG. 1, performed on the presently disclosedexemplary embodiment such as represented by present FIG. 5A;

FIGS. 6A and 6B are perspective and cross-sectional views, respectively,of another exemplary embodiment of the presently disclosed subjectmatter, involving molded packaging technology, for relatively reducingelectro-mechanical noise, and FIG. 6C is a graph of testing resultingfrom use of a testing arrangement as represented by present FIG. 1,performed on the presently disclosed exemplary embodiment such asrepresented by present FIGS. 6A and 6B;

FIGS. 6D through 6F show conceptual cross-section views of threedifferent respective exemplary embodiments of capacitors and solder padson mounting substrates; and FIG. 6G shows graphically acoustic outputsof exemplary embodiments as Peak Sound Pressure Level, in dB;

FIG. 7A is a representative example of an 8-terminal MLCC device inaccordance with the prior art device designs of present FIGS. 2A through2D;

FIG. 7B is a perspective view of another exemplary embodiment of thepresently disclosed subject matter, involving side terminal technology,for relatively reducing electro-mechanical noise, and FIG. 7C is a graphof testing resulting from use of a testing arrangement as represented bypresent FIG. 1, performed on the presently disclosed exemplaryembodiment such as represented by present FIG. 7B;

FIGS. 8A through 8C are perspective and component side elevational andboard side elevational views, respectively, of another exemplaryembodiment of the presently disclosed subject matter, involvingpre-mounted MLCC transposer technology, for relatively reducingelectro-mechanical noise, and FIG. 8D is a graph of testing resultingfrom use of a testing arrangement as represented by present FIG. 1,performed on the presently disclosed exemplary embodiment such asrepresented by present FIGS. 8A through 8C; and

FIG. 9 is a graph of comparative sound pressure testing resulting fromuse of a testing arrangement as represented by present FIG. 1, performedon presently disclosed MLCC devices pre-mounted on a substrate such asrepresented by present FIGS. 8A through 8C.

Repeat use of reference characters throughout the present specificationand appended drawings is intended to represent same or analogousfeatures, elements, or steps of the presently disclosed subject matter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As discussed in the Summary of the Subject Matter section, the presentlydisclosed subject matter is generally concerned with certain noiseaspects of mounted capacitor devices and related technology andmanufacturing and/or mounting methodology. More particularly, thepresently disclosed subject matter is concerned with improved designsfor certain capacitor components and component assemblies associatedwith the implementation of surface mountable devices, and particularlyas relates to providing low noise capacitors and related methodologies.

Selected combinations of aspects of the disclosed technology correspondto a plurality of different embodiments of the presently disclosedsubject matter. It should be noted that each of the exemplaryembodiments presented and discussed herein should not insinuatelimitations of the presently disclosed subject matter. Features or stepsillustrated or described as part of one embodiment may be used incombination with aspects of another embodiment to yield yet furtherembodiments. In additional, certain features may be interchanged withsimilar devices or features not expressly mentioned which perform thesame or similar function.

Reference will now be made in detail to exemplary presently preferredembodiments, and for which FIG. 1 illustrates a schematic view of anexemplary presently-devised test arrangement generally 10, for testingof either prior art devices or devices constructed and/or mounted inaccordance with the presently disclosed technology. Such a capacitordevice generally 12 may be surface mounted or otherwise positionedrelative to a substrate generally 14 such as a printed circuit board. Inthe arrangement devised, copper supports generally 16 are provided onrespective sides of board 14 and may be energized during testing asrepresented by the indicated lead wires, and as will be understood bythose of ordinary skill in the art from the illustrations of presentFIG. 1.

A high-precision microphone generally 18 may be mounted a given distancegenerally 20 from the substrate 14. In an exemplary arrangement, a 2 mmdistance may be practiced relative to substrate 14, which may comprise a100×40×1.5 mm PCB. The surface mounted device generally 12 to be testedmay include various case sizes, such as 0201 through 1206.

The device to be tested may be, for example, solder reflowed to pads inthe center of the substrate. Use of the copper brackets 16 facilitaterepeatable placements of test substrates, with the microphone positionedon the opposite side of the substrate from that where the device to betested is mounted. A foam enclosure (not shown) may be provided aroundthe entire arrangement to reduce stray noise. With such an arrangement,the noise floor may be approximately about −6 dB, over a frequency rangeof interest of about 1 to 10 kHz.

In an exemplary arrangement, a Brüel & Kjær ½″ Microphone and Preampwere used in conjunction with a Brüel & Kjær Photon+ Signal Analyzer. AnHP 33120A Function Generator was used in conjunction with a Krohn-HiteModel 7500 Amplifier used to energize the test item with a 1-5 kHz SweptSine Wave; 3.15 VAC; 3.15 VDC; 0.1 s sweep rate. Most high CV capacitorstested had a 6.3V rating so test waveforms were set up to operatebetween 25% and 75% of 6.3 volts (about 1.6 to 4.7V).

While various set-up arrangements may be practiced, those of ordinaryskill in the art will appreciate that such microphone geometry andplacement provides an effective arrangement for capacitorelectro-mechanical noise testing, as represented by the concentrichalf-circle vibration waves illustrated in FIG. 1, emanating from boththe tested device 12 and the board 14.

As otherwise discussed herein, present FIGS. 2A, 2B, 2C, and 2D arevarious perspective and cross-sectional views of prior art multi-layerceramic capacitor (MLCC) devices, such as shown by FIGS. 2 and 3 ofcommonly owned U.S. Pat. No. 7,352,563. Such a MLCC may have, forexample, a Ni—Sn plating over a thick film Cu termination, inconjunction with a main body having interdigitated or interlaced pluralsets of electrode structures 22 and 24 of opposite polarity, as will beunderstood by those of ordinary skill in the art.

FIG. 3 is a graph of comparative sound pressure testing resulting fromuse of a testing arrangement as represented by present FIG. 1, performedon existing MLCC devices such as represented by present FIGS. 2A through2D. It graphs sound pressure level (SPL) (in dBs) versus appliedfrequencies (in Hz). The noise floor is what's represented by an emptytest chamber. As shown, a representative peak occurs per this testing at49.3 dB, within the tested frequency range of between 1 to 9 kHz. Acorresponding Figure of Merit indication is made out by the area underthe SPL curve and in this instance amounts to about 2.0 Pa·Hz. Theessentially same testing arrangement is used in conjunction withexemplary embodiments of the presently disclosed subject matter, asotherwise discussed herein.

FIGS. 4A and 4B are simple schematic representations of aspects ofmounting MLCC devices on printed circuit boards (PCBs), in accordancewith presently disclosed subject matter, and which contribute toreductions in electro-mechanical noise from such combinations. Asrepresented, a representative presently disclosed MLCC device generally26 is received (mounted and/or supported) relative to a supportingsubstrate generally 28 (such as a PCB). FIG. 4A represents technologicalapproaches which provide a dampening aspect in such combination asbetween device 26 and substrate 28. FIG. 4B represents resulting forcereductions which can otherwise cause mechanical forces and resultingnoise in the supporting substrate. As schematically shown by suchembodiments, there is a reduction in the supportive/connective footprintas between the device 26 and substrate 28, resulting in particularizedarrangements of reduced vibration force transmission between the two.

FIG. 5A is a cross-sectional view of an exemplary first embodiment ofthe presently disclosed subject matter, involving compliant terminationtechnology, for relatively reducing electro-mechanical noise. FIG. 5B isa graph of testing resulting from use of a testing arrangement asrepresented by present FIG. 1, performed on the presently disclosedexemplary embodiment such as represented by present FIG. 5A, andcomparing such results with results for a prior art thick Cu filmterminated device, such as represented in prior art present FIG. 2D.

In contrast to the thick film copper termination of prior art FIG. 2D,the presently disclosed FIG. 5A exemplary embodiment has an Ag-Polymertermination over a relatively thinner Cu layer (or “flashing”). Suchmore compliant polymer termination acts as “cushion” and dampens againstthe coupling of vibrations between the capacitor device and the PCB.While Ag-polymer is shown as a specific example, it is to be understoodby those of ordinary skill in the art from the complete disclosureherewith that more generally conductive polymer or polymer may bepracticed rather than being restricted to only Ag-polymer.

As shown by present FIG. 5B, test results for the presently disclosedembodiment of present FIG. 5A are represented by the right sidedatapoints, and compare with the left side datapoints from the prior artdevice (of FIG. 2D). A reduction of about 6 dB is achieved. Since the dBaxis is logarithmic, the reduction represented is on the order ofmagnitude of cutting the transmitted sound (SPL or noise) by half. Thethick film copper termination prior art embodiment (FIG. 2D) has about a120 GPa Modulus while the presently disclosed subject matter exemplaryembodiment of FIG. 5A has a less than 5 GPa Modulus. Such exemplaryembodiments for testing purposes involved 0805 10 microFarad MLCCdevices. Thus, the compliant termination presently disclosed embodimentis shown to have a significant noise reduction over the prior artembodiment.

FIGS. 6A and 6B are perspective and cross-sectional views, respectively,of another exemplary embodiment of the presently disclosed subjectmatter, involving molded packaging technology, for relatively reducingelectro-mechanical noise. FIG. 6C is a graph of testing resulting fromuse of a testing arrangement as represented by present FIG. 1, performedon the presently disclosed exemplary embodiment such as represented bypresent FIGS. 6A and 6B.

The subject molded package embodiment involves use of a lead frame todecouple capacitor distortion from the PCB. The length of the wire pathand the respective top and end attachment points as shown provide suchdecoupling. Also, a polymer coating helps to dampen device noise.Further, a so-called A-case package mounts as LGA (land grid array)style package on 0805 solder pads.

FIG. 6C graphical represents test results between a standard 0805 MLCCdevice (of the style as presented by present prior art FIG. 2D) versusan 0805 A-case sample, using the molded packaging technology presentlydisclosed, for a 22 microFarad device. As shown, the presently disclosedtechnology provides anywhere from a 12 to 28 dB reduction in the peakSPL, thus representing significant improvement over the prior art.

FIGS. 6D through 6F show conceptual cross-section views of threerespective different exemplary embodiments of capacitors and solder padson mounting substrates. FIG. 6D is a multilayer ceramic capacitor deviceon corresponding mounting pads, that is, an 0402 MLC mounts on padsdesigned for an 0402 device, 0603 MLC on 0603 pads, and so forth. FIG.6E shows a given MLC capacitor inserted in a molded device that isphysically larger than MLC itself, such that the molded device mounts onsolder pads designed for that case-size molded part. Per EIA industrystandards, R- and N-case size molded devices mount on 0805 solder pads,A-case molded parts mount on 1206 solder pads, and B-case molded devicesmount on 1210 pads, and so forth. In particular, such industry standardmounting allows solder fillets to form on the ends of the moldeddevices, as shown conceptually in FIG. 6E. However, if molded devicesare mounted on solder pads designed for one case size smaller chip, asshown conceptually in FIG. 6F, then solder fillets on the end of themolded device are substantially eliminated. In other words, R- andN-case size molded devices would be mounted on 0603 pads, A-case deviceson 0805 pads and B-case devices on 1206-pads, and so forth.

As shown graphically in FIG. 6G, it is possible to compare the acousticoutput as Peak Sound Pressure Level, in dB, of a typical 0603 MLC withcapacitance in the range of 2.2 to 22 μF mounted on 0603 mounting pads;an A-case molded device containing MLC inserts of the same range ofvalues molded on industry standard 1206 mounting pads; and those A-casedevices mounted on smaller 0805 pads that eliminate solder-end fillets.The acoustic output of A-case molded devices is reduced relative to thebare MLC inserts, and furthermore the acoustic output of the moldeddevice mounted on solder pads that eliminate the solder-end fillets isreduced relative to the molded device mounted with solder fillets.

As shown graphically in FIG. 6G, it is possible to compare the acousticoutput as Peak Sound Pressure Level, in dB, of a typical 0402 MLC withcapacitance in the range of 0.1 to 10 μF mounted on 0402 mounting pads;an R-case molded device containing MLC inserts of the same range ofvalues molded on industry standard 0805 mounting pads; and those R-casedevices mounted on smaller 0603 pads that eliminate solder-end fillets.The acoustic output of R-case molded devices is reduced relative to thebare MLC inserts, and furthermore the acoustic output of the moldeddevice mounted on solder pads that eliminate the solder-end fillets isreduced relative to the molded device mounted with solder fillets. Table1 lists several examples of industry standard molded devices and MLC'sand non-standard Land-Grid-Array (LGA) mount pad geometries thatminimize solder-end fillets to reduce acoustic output.

TABLE 1 Industry Standard Low Noise “LGA” Molded EIA MLC Mounting PadMounting Pad Device Insert Size for Size for Size Size Molded PartMolded Part A-Case 0603 1206 0805 B-Case 0805 1210 1206 or 0805 R-Case0402 0805 0603 N-Case 0402 0805 0603

FIG. 7A is a representative example of an 8-terminal MLCC device inaccordance with the prior art device designs of present FIGS. 2A through2D. FIG. 7B is a perspective view of another exemplary embodiment of thepresently disclosed subject matter, involving side terminal technology,for relatively reducing electro-mechanical noise. FIG. 7C is a graph oftesting resulting from use of a testing arrangement as represented bypresent FIG. 1, performed on the presently disclosed exemplaryembodiment such as represented by present FIG. 7B, and comparing resultsfrom such testing with testing on a prior art embodiment such as shownby present FIG. 7A. The side terminal exemplary embodiment utilizesreduction functionality and subject matter such as represented generallyby present FIG. 4B, with a relatively reduced coupling footprint. Again,reduction of about 6 dB is shown by the comparative test results ofpresent FIG. 7C.

FIGS. 8A through 8C are perspective and component side elevational andboard side elevational views, respectively, of another exemplaryembodiment of the presently disclosed subject matter, involvingpre-mounted MLCC transposer technology, for relatively reducingelectro-mechanical noise. FIG. 8D is a graph of testing resulting fromuse of a testing arrangement as represented by present FIG. 1, performedon the presently disclosed exemplary embodiment such as represented bypresent FIGS. 8A through 8C, and compared with a prior art MLCCembodiment such as the design of present FIG. 2D. Again, an 0805 sizedevice is used for some of the comparison datapoints, while (as shown)0603 size embodiments are utilized in some instances. The term“transposer” is used because literally the location of the mounting padsis transposed for a given case size MLCC to pads for smaller case sizeddevices. This results in a reduction in the effective bonding area, adecrease of the span between mounting pads, reduction of the LGA-typesolder fillet, and an increase in the MLCC device stand-off.

For example, FIG. 8B illustrates from the component side, an 0603footprint generally for the capacitor mounting pad generally 30 as usedwith solder mask 32 for mounting on representative substrate 34.However, FIG. 8C, illustrating from the board (or substrate) side, showsthat the transposer mounting pad generally 36 results in an 0201footprint (generally dotted line area 38). Thus, the ElectronicIndustries Alliance (EIA) mounting size is transposed by suchembodiments. Note that EIA case size codes as discussed herein are withreference to inches. The following Table 2 reflects the variousreductions in effective bonding areas which may be achieved withpractice of such presently disclosed subject matter. Further, FIG. 8Drepresents graphical illustration of the significant peak SPL datareductions (on the order of 12 to 20 dB) achieved by such presentlydisclosed devices relative to prior art MLCC devices. Such FIG. 8D graphalso represents 60 to 90% reductions in the Figure of Merit (FOM) data.

TABLE 2 EIA MLC Transposed Size Mounting Size 1206 0603 0805 0402 06030201

Present FIG. 9 is a graph of comparative sound pressure level testingresulting from use of a testing arrangement as represented by presentFIG. 1, performed on presently disclosed MLCC devices pre-mounted on asubstrate such as represented by present FIGS. 8A through 8C. As shown,the peak SPL shown over the 1 to 9 KHz range is about 23.8 dB, which isfar less than the 49.3 dB peak SPL show in the graph of present FIG. 3.Likewise, the Figure of Merit is reduced to an area determination ofabout 0.4 Pa·Hz, down from the about 2.0 Pa·Hz datapoint obtained inconjunction with FIG. 3 testing. Comparison testing summaries relativeto such FIG. 3 graph for the four different exemplary embodiments ofpresently disclosed subject matter is set forth in the following Table3.

TABLE 3 Peak SPL Reduction FOM Reduction Compliant 7.5 dB    23%Terminal Molded MLC 12-28 dB 70-97% Side Terminal 5 dB    49% Transposer12-19 dB 60-90%

The following Table 4 summarizes the relative efficacy of presentlydisclosed embodiments of electro-mechanical noise (peak SPL) reductionrelative to size adjustment and cost factors. Such comparative aspectsmay tend to indicate selection of one particular presently disclosedembodiment over another for a particular application or set of userneeds/criteria.

TABLE 4 Size Cost E-M Noise SPL Adjustment Adjustment TechnologyReduction Factor Factor Compliant Good Low Low Termination (FIG. 5A)Molded MLC Excellent High High (FIGS. 6A-6C) Side Terminal Good LowModerate (FIG. 7B) MLC Very Good Moderate High Transposer (FIGS. 8A-8C)

While the presently disclosed subject matter has been described indetail with respect to specific embodiments thereof, it will beappreciated that those skilled in the art, upon attaining anunderstanding of the foregoing may readily adapt the presently disclosedtechnology for alterations or additions to, variations of, and/orequivalents to such embodiments. Accordingly, the scope of the presentdisclosure is by way of example rather than by way of limitation, andthe subject disclosure does not preclude inclusion of suchmodifications, variations, and/or additions to the presently disclosedsubject matter as would be readily apparent to one of ordinary skill inthe art.

What is claimed is:
 1. A surface mountable relatively low noisemultilayer ceramic capacitor (MLCC) assembly, comprising: a main bodyhaving a plurality of conductive layers of respective first and secondpolarities interleaved with a plurality of ceramic layers to formrespective pairs of opposing capacitor plates in a stacked arrangement;respective first and second polarity terminations on opposite ends ofsaid main body and electrically connected, respectively, to said firstand second polarity conductive layers; and one or more vibrationdampening members, wherein at least a portion of the one or morevibration dampening members is configured to be attached to a mountingsurface, wherein the one or more vibration dampening members comprise acompliant layer included with the terminations, wherein the terminationsinclude a first layer adjacent each opposite end of said main body andthe compliant layer is disposed over the first layer, and wherein thecompliant layer includes a polymer, and wherein the compliant layer isconfigured to dampen vibrations and reduce electro-mechanical noise suchthat the capacitor assembly has a figure of merit less than about 0.52Pa-Hz.
 2. The multilayer ceramic capacitor (MLCC) assembly of claim 1,wherein the compliant layer directly contacts the first layer.
 3. Themultilayer ceramic capacitor (MLCC) assembly of claim 1, wherein thecompliant layer comprises: a layer of compliant polymer.
 4. Themultilayer ceramic capacitor (MLCC) assembly of claim 3, wherein thecompliant polymer comprises: a conductive polymer.
 5. The multilayerceramic capacitor (MLCC) assembly of claim 1, wherein the compliantlayer comprises a silver-polymer.
 6. The multilayer ceramic capacitor(MLCC) assembly of claim 1, wherein the compliant layer comprises acopper filled polymer.
 7. The multilayer ceramic capacitor (MLCC)assembly of claim 1, wherein the compliant layer has a modulus ofelasticity of less than 5 GPa.
 8. A surface mountable relatively lownoise multilayer ceramic capacitor (MLCC) assembly, comprising: a mainbody having a plurality of conductive layers of respective first andsecond polarities interleaved with a plurality of ceramic layers to formrespective pairs of opposing capacitor plates in a stacked arrangement;respective first and second polarity terminations on opposite ends ofsaid main body and electrically connected, respectively, to said firstand second polarity conductive layers; and one or more vibrationdampening members, wherein at least a portion of the one or morevibration dampening members is configured to be attached to a mountingsurface, wherein the one or more vibration dampening members comprise acompliant layer included with the terminations, wherein the terminationsinclude a first layer adjacent each opposite end of said main body, andthe compliant layer is disposed over the first layer, and wherein thecompliant layer includes a polymer, and wherein the compliant layer hasa modulus of elasticity of less than 5 GPa such that the compliant layerdampens vibrations and reduces electro-mechanical noise such that thecapacitor assembly has a figure of merit less than about 0.52 Pa-Hz.